A Queens judge hit a former corrections officer with a maximum 25 years-to-life jail sentence for the cold-blooded murder of his infant son’s mother, who was gunned down, prosecutors said, because he was tired of paying child support.

Christopher Clavell, who guarded inmates at Rikers Island, will be on the other side of the bars until he is at least a senior citizen after he was sentenced for the pre-meditated murder of Barbara Perez, the mother of their infant son.

Perez, 32, was opening the back door to The Power Factory Gym in Ridgewood, where she worked as a manger, during the early morning hours of Aug. 11, 2000, when she was shot eight times in the head from behind and once in the chest, prosecutors said.

She was found on the floor of the gym.

The 20-year Corrections Department veteran wasn’t arrested for the crime until April 2011 investigators learned of statements he made implicating himself.

During the two-week trial, witnesses told the jurors that they remembered seeing Perez with bruises around her neck, and fearing for life because of Clavell, months before she was murdered.

“The defendant has now been punished for fatally shooting the mother of his young child,” Queens DA Richard Brown said in a statement. “He may have evaded the law for nearly 13 years but now justice has finally been achieved. I only hope that this sentence brings a measure of solace to her family.”

Clavell, 48, was convicted of planning the hit “over the course of weeks” after he repeatedly harassed and confronted Perez about the child support. Perez told family members that Clavell said he would sooner kill her than give her money, relatives said.

“The defendant has never shown any remorse and has disgraced his own family,” said Perez’ heartbroken brother-in-law, Ross Filler, said during the sentencing hearing. “He disgraced the justice system and he disgraced the Corrections Officers Union.”

“I worry for my little brother,” said Perez’s oldest son, Michael Morciglio, 27, as he choked back tears. “He never will know the pleasures of knowing our mother, her cooking breakfast, walks to school. He has no parents in his life. I have to make sure he doesn’t head down the wrong path.”

Queens Supreme Court Justice Joseph Zayas gave Clavell a chance to address the court before he issued the lengthy sentence, and one of Perez’ sisters quickly left the courtroom to avoid hearing his rant.

“People in this courtroom, lied,” Clavell said before reading a written statement. “They lied about me choking her, they lied about me talking to criminals about buying illegal guns, they lied.

“I believe in the justice system, but what happened in here was injustice,”